(1)The Secretary of State shall not use or interfere with any watercourse (including the banks of a watercourse), or any drainage or other works, vested in or under the control of the National Rivers Authority or any other drainage body within the meaning of the [1991 c. 59.] Land Drainage Act 1991 in the exercise of any of the powers conferred by this Act without the consent of the National Rivers Authority or that body.
(2)A consent required for the purposes of subsection (1) above shall not be unreasonably withheld; and if any question arises whether the withholding of consent is unreasonable either party may require it to be referred to an arbitrator to be appointed, in default of agreement, by the President of the Institution of Civil Engineers.